I think hardware buttons are needed. Yes we can do thing within the frontend but it's great when you can hit a button that performs a function and not have to look at the screen to do it. Plus there are applications outside of the frontend where the buttons can be useful as well.

Rotary encoder with push would be nice, but not a deal breaker, functions are implemented in the front end anyway,

same with hardware buttons, something tells me these would not see a lot of use as it would be another program/plugin to set up.

The only hard buttons required are for power and control of the LCD (input, menu, dim) get rid of the rest.

Agree with both arguments for SD, what to do?

Absolutely keep the full size USB and audio input.

I like the idea of a removable shade, but I was under the impression these screens were pretty good with sunlight, although capacitive touch will be a reflection problem.

Now if costs were not an issue:
add an HDMI input,
make USB input a USB3 capable socket with a pigtail I could run to either my motherboards USB3 port or to the LCD controller USB 2 hub.
add a second mic, both with ports on the rear so we can use the phoenix audio array kit.

TruckPC - gutted, being used for test setup
BoatPC - All in 1 in cuddy, N7 using VNC on dash, RR
BlazerPC - Nexus 7 with Timur's USBROM

Not sure why we'd really need USB3, and I don't think we need a input, menu, or dim button for LCD control. The dimming would be controlled via the car headlights as stated. Inputs shouldn't be an issue? You would have your CarPC as the main one, and it would automatically switch to reverse camera when you go into reverse. So all that goes automatically so I don't feel the need for input button. I would like to be able to turn off the screen though so I like that button.

Inputs shouldn't be an issue? You would have your CarPC as the main one, and it would automatically switch to reverse camera when you go into reverse....

Yes but what about the case where there's another video device that you wish to use? Auto switching to a reverse camera is great but there are times when I need to switch to another video source, like my ham radio.

A remote? Personally I think for instances like that I'd be perfectly happy using the little IR remote to switch inputs and go through menu's and stuff. I'd just prefer them not clutter up the already tight for space bezel.

Not sure why we'd really need USB3, and I don't think we need a input, menu, or dim button for LCD control. The dimming would be controlled via the car headlights as stated. Inputs shouldn't be an issue? You would have your CarPC as the main one, and it would automatically switch to reverse camera when you go into reverse. So all that goes automatically so I don't feel the need for input button. I would like to be able to turn off the screen though so I like that button.

It would give me the ability to use USB3 that my motherboard has. Just thinking of future proofing.

Dimming is kinda tricky, my frontend controls it for me, don't even need the headlight input for auto dimming, but it's a nice add on.
Then again, a button to black out the LCD, that's a good thought, press it once, blackout, press and hold, adjust brightness.
I agree that menu controls could be on a remote, just don't lose it.

Absolutely need to be able to switch video inputs, this should not be only accessible via a remote.

Again, buttons are tricky, you need some to control the LCD (source) , some to control the PC (power, volume) and you can't really have them share.

TruckPC - gutted, being used for test setup
BoatPC - All in 1 in cuddy, N7 using VNC on dash, RR
BlazerPC - Nexus 7 with Timur's USBROM

I also like Hdale85's suggestion of an IR remote. These come bundled with a lot of small LCD screens, and could be used for the LCD adjustment type tasks that you rarely need to perform. Skip it if it's going to significantly increase cost though.